The Nature of the Tectorial Membrane 149 



thinks, from his studies of the development of the membrane, that it is 

 improbable, d priori, for the membrane to float freely in the cochlear 

 duct. He did not carry his studies through the processes of the dis- 

 placement. Shambaugh, '07, assumes that the membrane is attached 

 to the inner supporting cells and that Hensen's stripe serves as a fascet 

 for this attachment. Kolmer, '07, often found the membrane attached 

 to various of the cells of the organ of Corti, but thinks these attach- 

 ments were artifacts. As early as 1872 Gottstein described "transparent 

 filaments" extending between the membrane and the inner supporting 

 cells of the organ of Corti of foetal cochleae, but considered these a.s 

 remnants of liquefying processes. Hensen, '07, in elaborating a theory 

 for tone perception, assumes and pictures the tectorial membrane as 

 extending free over the organ of Corti so that the hairs may brush 

 against it during the agitations of the endolymph, resulting in auditory 

 stimuli. The hairs have been described as sticking into the under sur- 

 face of the tectorial membrane. 



All the claims for the attachments of the membrane to any portion 

 of the epithelium of the spiral lamina (including the organ of Corti) 

 are based upon appearances presented in sections, and all describe the 

 connections as filamentous. The studies made here tend strongly to 

 the view that the membrane is attached only along its inner side and 

 only upon the labium vestibulare. 



(1) During the teasing away of the upper wall of the membranous 

 labyrinth to expose the membrane preparatory to its removal, the outer 

 portion could at times be easily seen under the dissecting microscope 

 to wave upward and downward in response to agitations produced in 

 the fluid with which it was covered during teasing. These movements 

 seemed to occur along its entire course. They occurred within very 

 small arcs and were suggestive of a certain amount of elasticity in the 

 membrane, causing it to retain its horizontal position because of the 

 attachment along its inner zone. If attached to the elements of the 

 organ of Corti, or even to the hairs alone, while individually such 

 attachments would be delicate and easily broken, it is hardly probable 

 that the necessarily great multitude of such attachments would so readily 

 disappear and allow the movements. 



(2) Sections of fixed and dehydrated material are but little more 

 suggestive of attachment of the membrane than they are of its being 

 free from the organ of Corti in the adult condition. The membrane is 

 alwavs more or less shrunken and distorted, and these effects of the 



